Yarn cutting device for circular knitting machines



Aug. 13, 1968 F. LONATI 3,396,559

YARN CUTTING DEVICE FOR CIRCULAR KNITTING MACHINES Filed Oct. 18, 1965 5 Sheets-Sheet 1 0' i I 11 Q Fig. 1

lNVENTOR- Aug. '13, 1968 F. LONATI 3,396,559

YARN CUTTING DEVICE FOR CIRCULAR KNITTING MACHINES 3 Sheets-Sheet 2 Filed Oct. 18, 1965 34 12a 22a M 20 F196 7 INVENTOR. L

Ti-ancesco I aged Aug. 13, 1968 F. LONA-TI 3,396,559

YARN CUTTING DEVICE FOR CIRCULAR KNITTING MACHINES Filed Oct. 18, 1965 3 Sheets-Sheet 3 3 2 1 24 25 l i i \Lr 29 I 27 INVENTOR. 6 fianeesablomti United States Patent 3,396,559 YARN CUTTING DEVICE FOR CIRCULAR KNITTING MACHINES Francesco Lonati, 28 Via Val Sorda, Brescia, Italy Filed Oct. 18, 1965, Ser. No. 497,212 Claims priority, application Italy, Nov. 18, 1964, Patent 739,403 3 Claims. (Cl. 66-134) ABSTRACT OF THE DISCLOSURE A yarn cutting mechanism for circular knitting machines with a dial assembly comprising means for retention and removal of yarns above the dial and two cutting units actuated by a transmission system cooperating with corresponding cams, said two cutting units being both mounted adjacent the dial assembly with cutting members inside the needle circle, one said unit being disposed with cutting means substantially horizontal and close to the dial and the other with cutting means vertically shiftable and arranged near the edge of the dial itself, and means being provided for giving the cutting blades an oscillatory motion during knitting.

This invention relates to a yarn cutting device for circular knitting machines.

Many thread or yarn cutting devices are known in the stocking manufacturing art which are designed to cut the yarn or threads at reinforcements, during yarn change at the welt or border and the like and when reinforcing.

Such yarn cutting devices tend to cut the yarns very close to the knitted article thus leaving small projecting thread ends which do not require a subsequent handtrimming.

However, the results obtained up to the present are not satisfactory, since in many cases the yarn ends projecting from the stockings, after the cutting are still too long. This particularly occurs in connection with the cutting of the yarn during knitting of the border or welt.

The above-outlined inconvenience could not be eliminated heretofore, and the stockings are today commercially available often with yarn ends projecting internally somewhat longer than necessary.

It is the main object of this invention to eliminate the aforementioned inconveniences in conjunction with the cutting means of known type by providing an apparatus adapted to cut the yarn ends very close to the knitted article, including during the border knitting phase and to operate in an accurate and safe manner thus avoiding needle breakdowns or jamming in case of wrong setting or undesired displacements.

It is a further object of this invention to provide a device having a remarkable efiiciency and accuracy adapted to be fitted on any circular knitting machine of the single or multi-feed type.

It is another important object of this invention to permit the manufacturing of seamless stockings of high quality and most accurate finish at low costs.

These and still other objects are attained by the yarn cutting device according to the present invention, comprising means for retention and removal of yarns arranged above the dial assembly and two cutting units actuated by transmission systems cooperating with corresponding cams, which yarn cutting device is characterized in that said two cutting units are both mounted on the upper part of the dial assembly with cutting members inside the contour of the needle cylinder, one of them being disposed with cutting means substantially horizontal and adhering to the dial assembly and the other with cutting means displaceable upwardly near the edge 3,396,559 Patented Aug. 13, 1968 "ice of the dial itself, means being provided for giving the cutting blades an oscillatory motion during the cutting operation.

Further features and advantages of the invention will become more apparent from the following detailed description of a preferred non-limiting embodiment of a yarn cutting device according to the present invention, reference being made to the accompanying drawings, in which:

FIGS. 1 and 2 show in plan view and mean vertical section, respectively, the upper portion of the circular knitting machine, provided with the yarn cutters according to this invention;

FIG. 3 is a perspective view of the mechanism shown in FIG. 1;

FIGS. 4 and 5 show the yarn cutting unit with vertical ly arranged cutting means in two side views taken from two different view points;

FIGS. 6 and 7 show the yarn cutting unit with hoiizontally arranged cutting means in side and in plan view, respectively; and

FIG. 8 shows in plan view a detail of the cutting means of the yarn cutting unit shown in FIGS. 6 and 7.

Referring now to the above figures, the yarn cutting device according to the present invention comprises two cutting units, indicated at A and B, respectively, consisting of vertical cutting means (FIGS. 45) and horizontal cutting means (FIGS. 678), both mounted on one single mechanical unit, so as to position the cutting means inside the contour of the needle cylinder. More precisely, the horizontal cutting means 1 of the cutting unit B are mounted on the dial 2 and the vertical cutting means 3 of the cutting unit A co-operate with a device supported by the stationary structure of the machine, thus being internal to the contour of the needle cylinder 4 (FIG. 2).

The cutting blades are then all located very close to the needles, while provision is made for a yarn retention and removal system which is, per se, well known, comprising a sucking mouth 5 and clamp block 6 connected to levers 6a, in turn, engaged with the springs 7, all mounted above the dial 2.

Both units A and B are actuated, as far as the cutting motion proper is concerned, by the shaft 8 (FIG. 1) driving via a pair of bevel gears 9 (FIG. 2) the vertical shaft 10 (FIG. 2) imparting rotation to the dial (not shown). Keyed on the shaft 8 are two cam discs 11 and 12 which are provided with corrugated inner surfaces 11a and 12a for the driving of the blades of the units A and B, respectively.

The cutting unit A consisting of vertical blades comprises an L-shaped support 13 which is fastened to the stationary structure of the machine outside the needle cylinder. On said support a small slide 3a carrying the cutting members 3 is mounted for vertical sliding.

The cutting unit A comprises a stationary outer blade 14 and a movable inner blade 15. Said inner blade 15 engages at one end with a hook like extension 14a of the stationary blade 14 (both blades 14 and 15 in this portion rub one against the other thus causing the cutting action) and at the other end with a follower in the form of a screw 16, which is adjustably mounted on a rocker lever 17. The latter is pivoted at 18 to the slide 3a carrying the cutting members 3. The rocker lever end opposite the one carrying the screw 16 abuts against an oscillating arm 19 which is, in turn, pivoted at 20 on the stationary structure of the machine. A plate 21 integral with the slide 3a is further provided which carries an adjusting screw 22 designed to check with a stopping pin 23 mounted on the support 13. By such an arrangement the cutting members 3 with the slide 3a as well as the plate 21 and lever 17 may be shifted in vertical direction over a short distance limited downwardly by the engagement between the screw 22 and the stopping pin 23 and upwardly by the adjustable screw 22a (FIG.

The slide 311 is urged downward by a spring 24 (FIG. 5) having one end fastened to a pin 24a projecting from the slide 3a and the other end fastened to the support 13. The upward motion of the slide 3a, and hence of the cutting members 3 together with the lever 17, is transmitted by means of a control lever 25 pivoted on a horizontal pin 26 and having one end 25a in engagement with a rod 27 cooperating, in turn, with a cam 28, and the other end 255 of forklike configuration in engagement with a pin 29 rigid with the slide 3a and crossing the support 13 at a slit (not visible in the drawing) cut out in the same.

The movable blade of the unit A is urged upwardly by the spring 30 (FIGS. 2-3) having one end connected at 31 with the stationary blade 14, and the other end fastened to a pin 32 rigid with the movable blade 15 and projecting, with the free end thereof through a slot formed in the stationary blade 14. The arrangement in such that that upper end of the blade 15 is urged upwardly by means of the spring 30 against the screw 16, and hence presses the other end of the lever 17 against the oscillating or skipping arm 19. The latter is provided with a projection 19a (FIG. 5) in contact with the corrugated surface 11a of the disc 11.

As may be easily understood, the rotation of the disc 11 causes an oscillation or skipping of the arm 19 which is transmitted via the lever 17 and the screw 16 to the movable blade 15. The latter accomplishes therefore small reciprocating movements in the vertical direction thereby accomplishing the yarn cutting at its lower end in cooperation with the extension piece 14a of the stationary blade 14.

As mentioned, the lever 25, which is suitably actuated by the cam 28 through the rod 27, causes the lowering and raising of the cutting members 3 in an appropriate moment together with the slide 3a and lever 17; the latter keeping, however, always in contact with the oscillating arm 19 (which does not move since it is pivoted at to the stationary structure), and therefore constantly receiving a skipping oscillatory motion from the disc 11.

As cutting members 3 are provided for vertical movement, the cutting portion moves near the needles when lowered, so as to effect the yarn cutting at a point very close to the needles. As shown in the drawing, the cutting portions of the members 3 are inserted inside the needle circle, and it is thus possible to cut the yarns close to the needles, leaving projecting yarn sections of desired length (FIG. 2 shows a yarn 3b during the cutting operation of the members 3).

The control lever relating to the assembly A is kept in contact with the rod 27 by a spring 33 having one end fastened to the lever itself and the other end secured to a pin 34 rigid with the stationary structure of the machine.

The cutting assembly, generally designated at B, comprises, as mentioned above, the horizontally arranged cutting means 1. More precisely, said cutting means consists of a stationary plate 35 mounted near the edge of the dial 2 (FIG. 8) and a movable blade 36 provided with a cutting tip 36a mounted for oscillation with scissors-like motion by means of a vertical pin 37 (FIG. 6).

The oscillatory motion of the blade 36 is transmitted through a pin 38 (FIG. 6) engaging the blade at a slot 36b formed in the movable blade itself, said pin 38 being fastened to a small arm 39 which is, in turn, rigid with a vertical shaft 40 mounted for rotation on the stationary structure of the machine.

Said shaft 40 is clamped on the upper part by a screw 41a in a substantially transverse wedge-shaped arm 41 which is provided with a small projection 41b adapted to engage with the corrugated surface 12a of the cam disc 12. The contact between the projection 41b and the cam 12 is ensured by a pin 42 (FIG. 7) which, by means of a spring (not shown) urges the arm 41 against said cam. At the side opposite the one on which the pin 42 acts, the arm 41 is engaged with the tapered portion of a lever 43 pivotally mounted at 44 on the stationary structure of the machine. said lever 43 is urged at one of its ends against the arm 41 by a spring 44a secured to a stationary point of the carrying structure.

The other end of the lever 43 engages a plate 45 fastened to a control lever 46. The latter is pivotally mounted on the aforesaid horizontal shaft 26 and is maintained in contact with a rod 47 by means of a spring 48, the rod 47 being, in turn, in engagement with the relief 49 of a control cam.

As it may be seen from FIGS. 3, 6 and 7, the cutting unit B may be put in operation by means of the control cam 49 which acts to lift the rod 47. In such event, in fact, there is, a small rotation of the lever 46 which via the plate 45 causes the lever 43 to accomplish a small angular displacement (in counterclockwise direction with reference to FIG. 7), so that the pin 42 moves the arm 41 toward the cam 12 (the tension exerted by the spring 44a overcomes that provided by the spring acting on the pin 42 under rest conditions). Conversely, when the rod 47 comes back to its rest position, the lever 43 is disengaged from the plate 45, and while rotating in clockwise direction (see FIG. 7) urges by means of spring 44a, the arm 41 and its projection 41b out of engagement with the cam 12, against the action exerted by the pin 42.

In the operative stage (when the rod 47 is in its upper position), the projection 41b of the arm 41 is in contact with the cam 12, and, due to the rotation of the latter, it oscillates, transmitting the oscillatory motion to the shaft 40 and then to the eccentric pin 38 and movable blade 36.

From the foregoing the operation of the device described will be apparent.

The vertical blade cutting members 3 are brought into working position under control of the cam 28 via the lever 25 which, in this step, causes the lowering of the slide 3a. The cutting action is exerted, as mentioned above, by the reciprocating motion transmitted to the movable blade 15 via the lever 17 set in oscillation by the rotation of the corrugated cam 11. At the end of the cutting step the members 3 are brought back to rest position by lifting of the slide 3a.

In a closely analogous manner the cutting member 1 of the unit B operates due to oscillation of the movable blade 36 controlled by the corrugated cam 12.

Obviously, the two units A and B may operate independently from each other and, depending upon the cutting operation to be executed, they may operate simultaneously in some cases.

It should be noted that the yarn cutting device according to the present invention has the advantage that all the cutting blades are arranged inside the contour of the needle cylinder, thus being adapted for circular knitting machines of either single or multi-feed types.

The yarn cutting occurs as necessary or desired, with cutting unit A operating when reinforcing, for example, and cutting unit B operating as needed during the knitting.

The cut yarn lengths are removed by the sucking mouth 5 which is used also to retain the yarns in cooperation with the clamp blocks 6 according to a system which is known in the art.

Many changes and modifications may be made in the cutting means according to the invention without departing from the scope of the concept defined by the appended claims.

I claim:

1. Yarn cutting mechanism for circular knitting machines having a dial assembly with a vertical main driving shaft for the needle cylinder thereof and including'two cutting units arranged within the needle circle, each of said units having a movable blade, one of such cutting units being horizontal and on the dial assembly and the other being vertical and operating in a vertical plane, wherein according to the improvement the mechanism comprises a common horizontal shaft (8) supported on the frame of the knitting machine, two cam discs (11 and 12) fixed on said common shaft (8) one of said cam discs being adapted to impart on oscillating motion to the movable blade of the horizontal cutting unit (36), the other of said cam discs imparting a continuous reciprocating motion to the movable blade of the vertical cutting unit (14), said cam discs being arranged at opposite ends of said horizontal shaft (8) and at a distance from one another, said common shaft having at one end thereof a toothed wheel (9) transmissively connected with the vertical main driving shaft for the dial assembly, the mechanism comprising further a common pivot (26), a first lever (25) for locating the vertical cutting unit in operative position, a second lever (46) for actuating the horizontal cutting unit, said first and second levers (25 and 46) being pivoted on said common pivot (26), said pivot (26) extending substantially parallel to said horizontal shaft (8) and cam means for actuating said first and said second levers.

2. A mechanism according to claim 1, wherein the cam discs (11, 12) have respective cam surfaces facing one another.

3. A mechanism according to claim 1, wherein the vertical cutting unit further includes a transmission system for transmitting a reciprocating motion to the movable blade (15), comprising a lever (19) extending substantially parallel to the cam disc (11) and pivoted to the frame of the knitting machine, said lever having a projecting portion (19a) in contact with the cam surface of the cam disc (11) and a smooth surface on the opposite side of said projecting portion (19a), the transmission system further comprising a pivotally mounted rocker lever (17) having at one end thereof in sliding contact with said smooth surface, the other end of said rocker lever (17 having a follower member transmitting a reciprocating motion to the movable blade (15) of said vertical cutting unit when said lever (19) receives motion from said cam disc (11) during rotation of the latter and transmits said motion to said rocker lever (17), and a vertically movable slide on which said rocker lever (17) and the supporting structure of said movable blade (15) are supported thereby to allow the reciprocating motion to be transmitted to said blade 15) in different vertical positions of said slide.

References Cited UNITED STATES PATENTS 1,863,720 6/1932 Lawson et al. 66-134 2,159,942 5/1939 Lawson et al. 66134 2,184,503 12/1939 Peloquin 66134 2,357,708 9/1944 Toone 66 134 3,113,443 12/1963 Billi et a1. 66145 FOREIGN PATENTS 114,288 11/ 1941 Australia.

742,536 12/1955 Great Britain.

971,730 10/1964 Great Britain.

ROBERT R. MACKEY, Primary Examiner. 

